The process of relocating residents out of the Schubart Park flats in central Pretoria continued on Sunday after the flats were declared unsafe, the city of Tswane said.
Processing of registrations for the move continued until late on Saturday, said spokesman Peter de Necker.
About 200 of 800 residents had registered for alternative accommodation by late Saturday.
"We think some of those who are reluctant to register may be illegal immigrants... which makes it difficult in terms of the law," he said.
Many had arranged their own accommodation.
De Necker said only one foreigner had come forward to register, and could not provide an official passport document.
Schubart Park residents began protesting on Wednesday claiming they had no water or electricity for two weeks.
Tyres were burnt inside the building, residents threw bricks and bottles onto the street and a mobile toilet and car were set alight.
Police arrested 79 people for public violence. The city began relocating residents to shelters in Salvokop and Saulsville, west of Pretoria, on Friday.
Women with children were being given priority. The relocation sparked a protest by hundreds of angry Saulsville residents.
"We think the Saulsville residents are concerned about an influx of illegal immigrants into their area," De Necker said.
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